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Temporary Wiring -- Art. 305 Choose the best answer: 1. If you must provide a 60A, 120/240V temporary feeder for work on the 15th floor of a high-rise building under construction, which of the following cabled wiring...

Yes, it’s true. Sec. 240-3(d) (the former Table 310-16 obelisk note) doesn’t apply to pure motor circuit conductors sized in accordance with Sec. 430-22(a). The drawing you see to the right (available in...

General wiring rules -- Art. 300 Choose the best answer: 1. Which of the following methods provides acceptable mechanical protection against abrasion of Type NM cable when you run it through pre-cut rectangular holes...

Sizing wye-delta conductors to a hermetic refrigerant compressor don't follow the same rules as regular motor conductors in similar use — an error in the NEC. We received an interesting series of questions about...

Choose the best answer: 1. Suppose you install a 13.8kV, 480Y/277V transformer and secondary panel with a main disconnect on the top floor of a 5-story office building. Assume no effectively grounded building steel...

Sec. 250-24(a)(5) is one of the more fundamental Code rules, and perhaps one of the most misunderstood at the same time. Often referred to as the "single-point grounding rule," this is the prohibition against making...